In a prior art video noise reduction circuit, shown and described in Copending U.S. patent application Ser. No. 389,041, filed June 16, 1982, titled "Noise Reduction Circuit for Video Signals", invented by A. Hirota and assigned to the same assignee as the present invention, the input video signal is filtered through a low-pass filter to reject noise components. Concurrently, the input video signal is delayed with respect to the signal applied to the low-pass filter and desctructively combined with the output of the filter to provide a difference signal to a limiter to generate an offset voltage. This offset voltage is combined with the non-delayed video input signal.
However, due to the large value of rise time involved in the low-pass filter, the prior art noise reduction circuit generates an unwanted white area before the occurrence of a black-to-white transition and an unwanted black area before the occurrence of a white-to-black transition. The latterblack area is particularly noticeable and degrades image quality.